1. Field of the Invention
This invention relates to network systems and, more particular, to determining availability in a network system.
2. Description of the Related Art
Individual computers are commonly coupled to form a computer network. Computer networks may be interconnected according to various topologies. For example, several computers may each be connected to a single bus, they may be connected to adjacent computers to form a ring, or they may be connected to a central hub to form a star configuration. These networks may themselves serve as nodes in a larger network. While the individual computers in the network are no more powerful than they were when they stood alone, they can share the capabilities of the computers with which they are connected. The individual computers therefore have access to more information and more resources than standalone systems. Computer networks can therefore be a very powerful tool for business, research, or other applications.
Computer applications are becoming increasingly data intensive. Consequently, the demand placed on networks due to the increasing amounts of data being transferred has increased dramatically. In order to better manage the needs of these data-centric networks, a variety of forms of computer networks have been developed. One form of computer network is a SAN (Storage Area Network). SANs connect more than one storage devices to one or more servers, using a high speed interconnect, such as Fibre Channel. Unlike in a LAN (Local Area Network), the bulk of storage in a SAN is moved off the server and onto independent storage devices which are connected to the high speed network. Servers access these storage devices through this high speed network.
The management of a computer network is often a complex and challenging task. Consequently, management tools are required to help network managers decide how best to allocate time and resources in order to minimize potential sources of network downtime. A reliable, valid measure of network availability can be a valuable tool in managing computer networks.
Various availability analysis techniques have been developed in order to predict failure probabilities for computer networks. One availability analysis technique is to monitor the performance of one or more components. If a component's performance drops below a certain threshold, a service technician may be called out to repair or replace the component that is not performing adequately. Other availability analysis techniques are used during system design in order to determine what system components and what system configurations will provide a desired level of system performance. These techniques typically involve simulating a proposed design and analyzing the availability of the proposed design under different circumstances. Similar simulation tools may be used when determining how many local spares of certain components should be kept in stock for a particular system.